3d floating support system and related geometry-detecting machine of slender articles

ABSTRACT

A support system of a slender article in a geometry-detecting machine includes a plurality of vertical constraint points ( 1 ) with which the slender article is in contact, wherein the vertical constraint points ( 1 ) are coupled in pairs by interconnection arms ( 4 ) in turn including a constraint joint ( 3, 5 ) provided with a universal joint mechanism which leaves, to the arms ( 4 ), two rotational degrees of freedom ( 32, 34 ) along two orthogonal axes passing in the proximity of the longitudinal axis of the article, the constraint joints ( 3, 5 ) possibly being themselves similarly coupled in pairs until converging, in a multiple-layer sequence, towards a single constraint point.

FIELD OF THE INVENTION

The present invention relates to a support and three-dimensionalbalancing system of slender, generally skewed, articles to be used forthe accurate detection of their geometric shape.

TECHNOLOGICAL FIELD OF THE INVENTION

As is known, the mechanical manufacturing industry makes extensive useof slender semifinished products, generally made of metal and othermaterials, for the manufacture of more complex products. In particular,for the turning and moulding processes, without limitation thereto,slender semifinished products having different types of section (round,square, hexagonal, etc.) are widely used.

The characteristics of the slender semifinished products are related tofour main areas: geometry of the product, chemical and physicalcomposition of the material, surface finish and chemical, physical andmechanical characteristics. In each of the above-mentioned areas,established specifications are a compromise between the manufacturingissues of the product, the cost for the achievement of saidcharacteristics and the actual needs of the subsequent processes,determined both by machining processes and by the requirements of thefinal application.

The most common semifinished products in the engineering industry,without limitation thereto, are products in the form of bars intendedfor turning and/or moulding, usually having a length of 3 meters whichprovides a good compromise between handling of the semifinished productand amount of semifinished product to be treated for each processingcycle. Also, it is possible to find longer bars, up to 4, 5 or 6 meters,above which stock management and transport become difficult, or shorterbars, for which the time spent to load the bar to be processed isdisadvantageous. These articles are commonly marketed in variousmaterials, both metallic (steel, brass, aluminium, titanium, etc.) andpolymeric (polyethylene, polypropylene, PVC, Teflon, etc.) andnon-metallic (ceramic, glass, composite or sintered materials etc.).

For the scope of this invention it is necessary to deepen the subject ofthe geometry of the semifinished product. The bars have a slendercylindrical geometry, i.e. the dimensions of the base are “small” withrespect to the height of the cylinder. The most common shapes of thebase are circle, hexagon, square and rectangle; they can be either solid(bars) or hollow (tubes) and are required for processes where the usertakes advantage of the savings due to the execution of the sectionshape. For example, the round section is used for threads, shafts etc.;the hexagonal section for nuts, bolts etc. Remarkable importance isgiven to the respect of the dimensional specifications because, if suchcharacteristics are guaranteed by the manufacturer, the user will beactually able to avoid processes to obtain the right size to thespecific article; for example, in the case of round-sectional bars, theyare produced and marketed also with h7 tolerance, with very lowcircularity errors, allowing to realize finite shafts by simply cuttingand processing the workpiece end.

The main processings made on these semifinished products are lathemachining. The turning technologies are evolving very quickly andperformances, in terms of rotation speed and cutting features of tools,are considerably increasing. During turning, the bar is loaded on amachining axis on the back of the lathe and is set in rotationaccordingly for the entire length, as the machine performs a turningoperation. The most modern machines are able to perform machining withrotational speeds of 5,000, 8,000 or even 10,000 revolutions per minute,depending on the workability of the material. These rotational speedsare considerable and require that the semifinished product to have avery accurate “straightness”, in order to minimize problems of vibrationand, ultimately, of machining precision.

In order to have a method to unify the evaluation of the “straightness”,regulators have agreed for several years some definitions that will bereferred to below, and have gathered them into the European standard EN12164. This standard defines (for semifinished products in bars having adiameter from 10 mm to 50 mm and a length greater than 1000 mm) that thedeviation from straightness is the curvature (arc depth) with respect toa given theoretical line when the semifinished product lies on ahorizontal plane; this standard also indicates the limit values, whichshould not be exceeded, in mm/m: in the common jargon, a fraction of the“DIN” (meant as a reference to the norm EN12164DIN, i.e. the Germantransposition of the European standard) simplistically represents alevel of quality, with respect to straightness, of the same article (1/3DIN is a better quality of 1/2 DIN, and so on).

After several years of engineering studies on technological issuesrelated to the straightness of the articles, the Applicant concludedthat the above-mentioned standard cannot be considered suitable nowadaysto outline significant values of “straightness” for the currenttechnological production levels. The standard states that the detectionof the arc must be made when the semifinished product is lying on a flatsurface without taking into account that the established maximumcurvatures —that the modern manufacturing processes even tend todiscard—are almost cancelled by the effect of resting on the referenceplane due to the transverse friction: the actual deviations aretherefore almost undetectable. The relationship between the density andYoung's modulus, especially of metal alloys, is such as to cause thatthe deformation due to its own weight is far higher to the curvaturesexamined for qualitative purposes.

Basically, if a product lies on a flat surface, this product tends topresent a flat conformation despite its curvature, thus making itimpossible to determine it, just as outlined in the standard. In asimilar way, on the horizontal plane, friction becomes predominant withrespect to the possibility of the elastic return imposed by the smallcurvatures to be examined.

The issue of straightness was explored technologically in many fields,especially when the slenderness of the products causes the relationshipof density to Young's modulus and/or density to bearing friction to beunfavourable. This issue has always been an important engineering anddevelopment theme for technical solutions for measuring and analysis onproducts, both for quality control and for process control purposes.

In the prior art, there are several interesting embodiments aimed atmeasuring the straightness, both in terms of flatness and in terms ofstraightness. We find solutions and applications focused on more or lessoriginal methods of application of detection sensors, such as forexample in the documents EP 2527785, CN 102221354, EP 0352247, EP1447645, WO2006138220, WO09634251 or JP 61283804, where the mode ofsupporting the product is, however, not considered during measurement;obviously, these methods are convenient in applications where therelationship between density and Young's modulus or between density andfriction is favourable (for example in articles realized in carbon fibrecomposite), which often does not occur in case of slender metallicarticles.

Other solutions have been proposed focusing on how the product issupported with arrangements designed to control the action actuated byvertical supports in terms of force and displacement on the semifinishedproduct to be measured. There are various methodologies, with load cellmechatronic approaches as in the case of EP 2057438 or EP 1974179; withphysical approaches such as the physical floating in a fluid of the samedensity as in the case EP 1915323 or JP 063331339; or with fluidicapproach as in the case JP S5934109, where the slender body is supportedon a “bed” of isobar fluidic actuators. All the above-mentioned priorart, however, provides solutions mainly oriented to precision, as in thecase of the application of the sensors, or where the aim is to obtain anaccurate measure through the suspension of the article, in any case, byplacing the focus on the unique attempt to balance the negative effectsof gravity on the measurement of the article.

EP 2803942 also discloses a complex supporting system of slenderarticles, which simply, faces the need to manage a plurality ofarticles.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the limitations ofthe prior art by providing a support system for slender articlesallowing the same to freely assume their geometric shape, regardless ofexternal constraints, so as to be able to measure the real geometry ofthe pieces.

This object is achieved with a system as described in its essentialfeatures in the attached main claim. Other preferable aspects aredescribed in the dependent claims.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the invention will anyhow be moreevident from the following detailed description of a preferredembodiment, given by mere way of non-limiting example and illustrated inthe accompanying drawings, wherein:

FIGS. 1A and 1B are schematic figures which represent an exemplaryslender body, with circular and polygonal cross-section, respectively;

FIGS. 2A and 2B are schematic views, respectively a perspective andexploded view, of a support system according to an embodiment of theinvention;

FIGS. 3A, 3B, 3C are schematic side elevational views of the variousembodiments of the support system according to the invention;

FIG. 4 is a partial enlarged view of FIG. 2A, in which the instantaneousrotation axes are marked;

FIG. 5 is a schematic side elevational view of a different systemsupport mode according to the invention;

FIGS. 6-7 are schematic elevational side view of various configurationsfor a geometry-detecting machine using the system according to theinvention.

DESCRIPTION OF THE CURRENTLY PREFERRED EMBODIMENTS

The long research carried out for finding a workable solution to fulfilthe purpose of performing measurements which are precise, accurate andindustrially advantageous has led the Applicant to conceive a particularsolution that overcomes the limitations of the known art. To better getinto the specifics of the solution, it is necessary to make a smalldigression on precision and accuracy.

The precision of a measurement is defined by the statistical dispersionof the detected values compared to the average value of themeasurements; a more precise measurement of another measurement willhave less distant values from the average value of the same values, withrespect to a less precise measurement that will have more scatteredvalues, i.e. with a greater standard deviation. In the generaltechnique, precision is linked to the quality of the used sensor withrespect to the expected resolutions for the determination of thephysical quantity to be examined: for example, a laser triangulationfeeler is more precise than a mechanical feeler with position detection(for example of the resistive type). On the other hand, accuracy relatesto another aspect of the measurement, i.e. the distance of the detectedvalue, single or average, compared to the actual value. The latterconcept is an essential point for the system shown here, as the objectof the application is to provide a device capable of obtaining a value,which is as close as possible to the actual value, as only this valuecan be used both for quality control analysis, and for process controlactivities.

The first consideration to be made is that in a slender article notcomplying with straightness conditions, the site of the centres of thesections composing the article constitutes a skew curve, i.e. ageometric site whose osculating planes lie on several levels. Theproduction processes of the articles are such that the osculating planestend to be slightly divergent, but the experimental experience has shownthat even minor modifications of these planes tend to degrade theaccuracy of the measurement.

In differential geometry, a theorem is known (fundamental theorem of thetheory of curves in space) stating that if a parameterized curve withrespect to the arc length with curvature and torsion exists, such acurve is unique, except for rigid motions in space. This theorem makesus understand the importance of considering the slender and skewedbodies as a development of a curvature, rather than as simple Cartesianrepresentations; this mathematical concept has prompted the Applicant toconsider that, by suspending a slender and skewed article in space witha device capable of accommodating the curvatures of the article alongits curvilinear abscissa, minimizing the bending effects along theFrenet triad opposing to the accommodation of the actual curves of theproduct, it is posible to actualize the object of letting the slenderarticle to assure a shape according to its unique form, regardless ofthe torsional angle or of its attitude in the inertial space.

The devised solution consists of a system of supports (verticalconstraints) for the bar, suitably designed to meet what is indicatedabove at the theoretical level. This system, allowing to accommodate thecurvatures on two orthogonal planes simultaneously and with the sametechnique to create the balances, allows the elasticity of the slenderarticle to express freely, so that the article itself, typically a bar,can take its actual shape, leaving all internal tensions neutral. Forthis reason, the system according to the invention is also calledfloating system (or 3D Floating System), to emphasize its ability tobalance the gravitational effects and leave the multi-planarcurvi-linear freedom of the article.

More precisely, it is necessary to realize an external interconnectedsupport so that it is possible to realize a set of specific balances.The device is comprised of a set of physical supports made so as tominimize the contact surface, giving also the possibility (sometimesindispensable) of not constraining to rotation the article in the pointof support (torsion). In fact, in many cases, an aspect to be examinedis the “twist” i.e. the torsion rate of the section along the site ofthe centres of the article; in this case, the absence or minimization ofthe torsional constain ensures high accuracy for the detection of thetwist.

The support points are mechanically connected to each other throughmechanical arms of variable length, which possess the characteristic ofbeing variable in manual or automatic mode, this latter aspect beingessential for the perfect balancing of the system. These arms, belowreferred to as ‘primary’, in turn possess a particular point, typicallymidway but changeable if necessary, in which a universal joint mechanismis inserted, leaving to the primary arm two degrees of rotationalfreedom along two orthogonal axes passing as close as possible to thecentre of the article.

In this way, the support points are connected in pairs through saidconnecting arms. These primary arms are supported in turn by secondaryarms having, at their respective ends, connections to theabove-mentioned universal joints of the primary arms; preferentially incentral position, but possibly also offset, each secondary arm alsohaving a further universal joint with two orthogonal axes passing asclose as possible to the axis of the bar or article. Such universaljoint serves as a connecting element of the secondary arm level.

The resulting arrangement is substantially a plurality of arm layerswhich split, with a fractal pattern, the supports; in each support thereis a cardan suspension (universnal joint) with axes of rotation centredas much as possible in the bar or article to be supported, leaving tothe supported arm only two rotational degrees of freedom.

The universal joint is essential to allow the whole support arrangementto accommodate the curvilinear multi-planar trend of the article,without opposing any reaction on two orthogonal planes. The layers canbe several and, consequently, can lead to a number of final supports forthe article equal to 2̂n; in order to avoid leaving a residual degree ofrotational freedom, the final ground support (i.e. on fixed referenceplane of the machine) of the floating 3D system can be made convenientlyin two points. We will then have 4 supports in the case of twolayers/levels, 8 supports in the case of three layers, 16 supports inthe case of four layers, and so forth.

The number of layers is determined based on the extent of desiredfractioning of the article support. It is not ruled out that in someapplications it may be sufficient to have only one layer of arms.

In this way, the support scheme develops symmetrically with respect tothe centreline of the bar or article to be supported.

A high fractioning is positive in order to minimize the size of the freespan, but it is negative for the increase in the mass of support groups,arms and universal joints. Preferably, the correct compromise providesfor an optimal number of three layers for metal bars with size of thesection from 5 mm to 30 mm and of a length of from 3 to 6 meters,without the mass being such as to reduce the natural frequency of thesystem too much.

It shall be to emphasize the importance of the universal suspensionarchitecture, which allows to minimize the resistance effect to the freeplacement in the space of the article because, compared to other knowntechniques, the support reaction of the article is transferred to therotational point through an arm which causes friction and unavoidablemechanical resistances to have a minimal effect on the flexuraldistension freedom of the article. This is an aspect which particularlydistinguishes the solution of the invention, as such friction isresponsible for accuracy errors inevitably present in the othersolutions of the known art. The application of the universal joints asarticulation means of the support arms provides a composition oforthogonal planes for sustaining and accommodating natural curvatures ofthe article causing, inter alia, the article to be possibly placedvirtually in the space in any position without the inertial effectsaffecting the curvature of the same.

The device according to the invention has peculiar characteristics,which are: 1) the compensation of the inertial effects on the bend isindependent of the article position in the space, that is independent ofthe position of the support system and of the twist of the skewed curveof the site of the centres with respect to the support system itself; 2)a correlation between the angles of the various arms connecting theuniversal joints with the interpolation values of the curvatures alongthe article; 3) a minimization of friction mechanical effects in theuniversal joints with respect to bendings of the article; 4) the abilityto operate in a direct way with free universal joints and in an indirectway with locked universal joints: in the latter case, the locking torqueis a function of the bending moments inside the article when held in theposition dictated by the angles imposed on the universal joints.

According to a variant of the invention, the universal joints aretherefore of lockable type, namely the axes of rotation are mechanicallylockable with a fixed attitude. In this case, stress/strain sensors(such as load cells or similar) are preferably provided, being able todetect the existing stresses around the axes of the universal joints.

All the above aspects allow us to understand how the system works andhow this allows to perform extremely accurate measurements of thegeometric shape of the article in the following two cases: with freeuniversal joints or with locked universal joints.

In the case of free universal joints, the article can express itsgeometric curvature leading to the neutral balance its internaltensions, since the universal joint suspension system allows to leavethe bending of the article on its curvature planes free, reacting to theweight at the intersecting points of the supports and balancing the twoorthogonal components. Applying this system to a geometry-detectingmachine, the detection can be carried out through different technicalmethods. For example, by reading in various positions along the lengthof the article with common punctual laser or profile reading sensors;through inductive, capacitive or eddy current sensors; the systemswithout mechanical contact are preferable with respect to the contactreading systems, because the latter entail an unavoidable application offorces altering the shape, compromising the extreme accuracy of thesystem.

A second possibility is to read the angular position of each rotation inthe universal joints, through angle reading sensors such as encoders,resistive readers, inductive readers or other readers commonly availablein the art such as the Hall effect ones or eddy current ones.

The two approaches have advantages and disadvantages that can beevaluated as follows: reading through laser systems external to thefloating system, especially if movable with extreme straightness guidesconstrained to granite backbones and/or associated with interferometersfor the precise and instantaneous correction of the relative position ofmeasurement, allow a very detailed reconstruction of the deformationwith longitudinal resolutions, even millimetric or submillimetric,however introducing the need for additional integrated systems; themeasurement through the reading of the universal joint rotations insteadallows to maintain an extremely low complexity of the architecture ofthe machine as a whole, providing the curvature value and mediating theintermediate values among the support points. It has been experimentallyfound that the latter case is more than sufficient for all qualitycontrol and process control activities.

In the case of locked universal joints, the 3D Floating System has allthe 2̂n supports perfectly aligned. At this point, making the articlerest on the system, this will exert forces on the supports through itsweight and the tensions produced as a result of the elastic tensiongenerated by the difference between the natural curvature and theperfect imposed straightness; its own weight will be counteracted by thesymmetrical bending of the arm and will not develop a torque at theuniversal joint. The restraining reaction of the universal joint lockingwill then be representative of the bending state as being proportionalto the natural curvature. Such torsional information can be obtained byembedding torsion sensors in the universal joint locking system, ofwhich the technique offers many possibilities both as strain gaugesensors and piezoelectric sensors; in this way, it is possible todetermine the deformation in a very accurate way through a “postprocess” of the tensional information by applying an elastic model ofthe material (knowing the Young's modulus and the inertia of thesection). It is to be noted that, also in the case of free universaljoint configuration, it is possible, starting from the geometry, todetermine the state of the tensile deformation based on the Young'smodulus and of the inertia of the section.

In any case, the splitted modular arrangement and the universal jointcoupling kinematic are the elements making it possible to perform themeasurements, thanks to which it can be said that the accuracy of thesystem is an intrinsic feature of the same. The precision is then afunction of the positional or tensile detection technologies integratedto the 3D Floating System or external thereto and will be chosenaccording to the expectations of the final application.

The option of using the system in the free or constrained form, makingit a “reversible” system, is an important and distinctive feature of thesystem as it can be used in combination with particularly precise anddetailed external laser systems, with integrated internal systems ofrotational position or even torque metering systems, such as to make the3D Floating System also completely autonomous in the measurements.

In terms of performance, it is stressed that the locked universal jointconfiguration allows measurements to be made with no moving parts and noexternal measuring instruments. This fact allows to carry out almostinstantaneous detections as it is possible to read the torque metricreactions immediately after the bar has been laid down.

Elastically coupled mass movements not being present, as in the case offree universal joints, there is no need to wait for the possible dampingof oscillations of the article before performing the measurements; inaddition, there is no need to wait for the completion of a movableacquisition step, due to the absence of a detecting step by movablesystems.

Another advantageous feature of the system is to have the support pointsof the article on the support arms as described above, while maintaininga degree of translational freedom along the arm itself.

Substantially, at each support point of the floating system, the articleis free to slide back and forth along its longitudinal axis.

This is a significant possibility because it allows to maintain thismovement constrained through the bar itself and/or through a suitablesleeve constrained to the ground and movable longitudinally. The sleeveallows in this way, with its suitably mobility controlled in anautomatic way, to vary the length configurations of the arms. The systemis thus also easily reconfigurable in the event of length change of thearticle to be measured. That is, it can be provided that each support ofthe system is vertically slidable within a guide sleeve integral to thefixed reference of the system. The support is however vertically movablein a consistent way with the underlying interconnection arm. The sleevecan be translated along the extension of the arm, possibly withmotorization means, varying the application position of the supportalong the length of the corresponding interconnection arm.

The distribution of the supports along the longitudinal axis of thesystem is preferably set on the basis of the calculated elastic model ofthe article, so as to obtain the perfect balancing. This operation canbe assisted by a suitably programmed or preset automatic system duringthe production stage of the system (if it is intended for fixed andpredetermined length of articles).

Experiments on the universal joint suspension system confirmed theaccuracy expectation expected from theoretical and conceptualconsiderations. From the tests, it was found that measuring the bars(for example of round section diameter of 10 or 12 mm made of brass,steel or aluminium, with an offset valve of 1.5 mm along about 3 metersof total length), these have shown variations of a few tens of micronswith the variation of their rotational position (i.e. torsion in Frenetnomenclature) demonstrating the fact that the measurement is neitherinfluenced by the gravitational bias nor from the kinematics of theuniversal joint suspensions; thus, the two support orthogonal planesallowed the bar to express its curvatures on osculating natural planesmaking them rotate rigidly with the rotation of the bar exactly asstated by the fundamental theorem of the curve in space theory.

The support system can also be equipped with an automatic system formeasuring the length of the bar and of the position with respect to theaxis of symmetry of the floating system, thus allowing processingthrough the elastic model (knowing the Young's modulus and the inertiaof the section) of the correction factors of the measurement for theextrapolation of the real balance shape. The types of the longitudinalposition detection can be laser optical or discrete light systems, aswell as feeler systems, depending on the desired technical choices.

The mechanical part of the system must be combined with an electronicpart for the management and the reading of the sensors, for dataprocessing and storage and possible sharing with third-party linesystems. Therefore, data can also be represented in graphic form orstored on mass storage devices, storing raw data and summary data, suchas, for instance, the offset on any length, and most commonly in form ofmm/m as inspired by the above-mentioned standard. Data can also berepresented graphically by successive sections in three-dimensionalshape, two-dimensional shape, or with scalar values of numericalsynthesis to better represent the information for quality control andprocess control activities. The system can be completed by automatichandling systems for cooperation and unloading of bars to and fromproduction lines or ware-houses.

The system can be equipped with rollers at the contact points with theslender article, for example of the longitudinal type in order to allowthe free sliding along the longitudinal axis of the article. Thispromotes the continuous use of the machine for bars in longitudinalmovement or for seamless products. The contact constraint with thesupports can also be a two-sided type.

The following will provide a more detailed disclosure with punctualreference to the accompanying figures. FIGS. 1A and 1B show twoexemplary bars 18 which are generically curved, wherein the followingare highlighted: the deflection 22, the base line 23, the curvilinearaxis 26 of the bar and the terminal sections 24 and 25 of a round,square and hexagonal type. In this representation, the article is seenwith a perspective such as to be represented in a compact form; inpractice, the typical dimensions are in the order of meters for thereferences 23 and 26, tens of millimetres for the references 24 and 25and millimetres for the reference 23.

FIG. 2A shows an embodiment of the system, which helps to understand theessential concept of the invention. The bar 18 lies on a system witheight supports 1 and three layers 8/4/2 with joints 3; the joints andthe supports are universal joint suspensions connected by arms 4. Thepoint 5 is the constraint point of the last arm to the ground (i.e. tothe fixed reference plane of the system). The axis of symmetry 19 of thesystem is also visible.

FIG. 2A shows more visibly the assembly logic of the parts constitutingthe universal joint suspensions provided in the support points 1 of thearticle, in the connection joints 3 between the arms 4 and in theconstraint to the ground 5.

FIG. 3 show a diagram of the support of the article 18 in two cases:with eight supports in FIGS. 3A and 3B, and with sixteen supports inFIG. 3C, respectively. In the latter case, the left part symmetrical tothe centre axis 19 is not shown. The support scheme provides a tree-typestructure in which the supports 1 at the first layer become four joints3 in the cases of FIGS. 3A and 3B and eight in the case of FIG. 3C, thenbecoming two joints 3 in FIGS. 3A and 3B, then constrained to the groundthrough the supports 5. In the case of FIG. 3C there is an additionallayer of four joints, before passing to the last layer with the groundconstraints 5. In these representations, it is possible to observe theinterconnection elements 4 between the support points 1 and between thejoint points 3. The scheme of symmetry with respect to the centreline 19of the bar is important.

In these figures, the interconnection between the joints of themechanical type should be noted, wherein hinges must be present in thesupport 1 and joint 3 points, allowing the free rotations of theinterconnection elements 4 (i.e. the arms). The symmetry of the systemwith respect to the centreline 19 is important; the position of thesupport points 1 may be non-uniform and the lengths of theinterconnecting elements 4 can be variable and controlled throughautomatic management systems.

FIG. 4 shows the axes of rotation of the universal joint suspensions,wherein the two orthogonal axes 32 and 34 and the torsion axis 33 areshown.

FIG. 5 shows a different embodiment of the invention, wherein thesupport system is in an operating configuration, rotated by 180 degreeswith respect to the axis of the bar 18. In this case, the verticalconstraints are working under tension rather than under compression;i.e. the vertical constraints hang the article from the top, and thenare subjected to tension action.

FIG. 6 shows an example of the system applied to a geometry-detectingmachine with an arrangement of eight supports 1 wherein the workinglogic of the interconnection elements 4 being balanced through therotations in the joints 3 as a result of the constraint-reaction forceson the article is evident. The figure shows the precision axis 27 andthe laser sensor able to acquire the measurements along the base line orthe curvilinear abscissa. The sensor 28 also has the function ofdetecting the length and position of the article with respect to thesymmetry of the support system, since such information may be useful toprocess curvilinear correction coefficients to compensate for thelengths and the asymmetry in the positioning. It is also possible toadopt side laser sensors for the detection on the horizontal plane ofthe article in the form of a bar, especially if associated with theapplication of the lateral free systems 21.

FIG. 7 represents a machine, which is an alternative to that of FIG. 6,wherein fixed sensors of different types (inductive, capacitive, eddycurrent) are provided on the horizontal plane, on the vertical planeand/or for the axial positioning of the article in the form of a bar.

In special configurations, it is possible to artificially unbalance thebalancing arms, in order to rebalance articles not having compliantlengths with respect to the preset configurations. Such unbalance is tobe understood as the application of elastic or constants forces to beimplemented in the joints in order to rebalance discrepancies betweenthe actual positions of the constraints and the ideal positions. Withthis logic, it is possible to fit devices which are external to thebalancing system for the application of forces to the article, in orderto compensate with special logics for the discontinuities at the endsand for the edge effects.

As can be understood from the above disclosure, thanks to theconfiguration of the invention, it is possible to have a support systemof a slender body providing ample freedom of adaptation, so as not toaffect the natural geometry during the detection operations of theactual geometric shape.

It is understood, however, that the invention is not to be considered aslimited by the particular arrangements illustrated above, whichrepresent only exemplary embodiments of the same, but different variantsare possible, all within the reach of a person skilled in the art,without departing from the scope of the invention itself, as defined bythe following claims.

1. A support system of a slender article in a geometry-detecting machineof the slender article, comprising: a plurality of vertical constraintpoints (1) with which said slender article is in contact with, whereinsaid vertical constraint points (1) are coupled in pairs byinterconnection arms (4) in turn comprising a constraint joint (3, 5)provided with a universal joint mechanism which determines, for saidarms (4), two rotational degrees of freedom (32, 34) along twoorthogonal axes passing in the proximity of the longitudinal axis of thearticle.
 2. The system as in claim 1, wherein said interconnection arms(4) have a variable length between said coupling points to the verticalconstraint points (1).
 3. The system as in claim 1, wherein saidvertical constraint points (1) leave at least one degree of torsionalfreedom (33) to said slender article.
 4. The system as in claim 1,wherein said vertical constraint points (1) leave at least one degree oftransversal freedom to said slender article.
 5. The system as in claim1, wherein said vertical constraint points (1) leave at least one degreeof longitudinal translation freedom to said slender article.
 6. Thesystem as in claim 1, wherein there are furthermore provided lockingmeans to inhibit said rotational degrees of freedom (32, 34) of saiduniversal joint mechanism, and sensor means for detecting the rotationstresses in said universal joint mechanisms in correspondence of therotation axes of said rotational degrees of freedom (32, 34).
 7. Ageometry-detecting machine of a slender article, comprising a framefeaturing a support system of the slender article and ageometry-detecting device adapted to detect the geometric shape of theslender article constrained on said support system, wherein said supportsystem is as in claim
 1. 8. The support system of claim 1, wherein saidconstraint joints are coupled in pairs until converging, in amultiple-layer sequence, towards a single constraint point.
 9. Thesystem as in claim 2, wherein said vertical constraint points (1) leaveat least one degree of torsional freedom (33) to said slender article.10. The system as in claim 2, wherein said vertical constraint points(1) leave at least one degree of transversal freedom to said slenderarticle.
 11. The system as in claim 2, wherein said vertical constraintpoints (1) leave at least one degree of longitudinal translation freedomto said slender article.
 12. The system as in claim 2, wherein there arefurthermore provided locking means to inhibit said rotational degrees offreedom (32, 34) of said universal joint mechanism, and sensor means fordetecting the rotation stresses in said universal joint mechanisms incorrespondence of the rotation axes of said rotational degrees offreedom (32, 34).
 13. A geometry-detecting machine of a slender article,comprising a frame featuring a support system of the slender article anda geometry-detecting device adapted to detect the geometric shape of theslender article constrained on said support system, wherein said supportsystem is as in claim
 8. 14. The system as in claim 8, wherein saidvertical constraint points (1) leave at least one degree of torsionalfreedom (33) to said slender article.
 15. The system as in claim 8,wherein said vertical constraint points (1) leave at least one degree oftransversal freedom to said slender article.
 16. The system as in claim8, wherein said vertical constraint points (1) leave at least one degreeof longitudinal translation freedom to said slender article.
 17. Thesystem as in claim 8, wherein there are furthermore provided lockingmeans to inhibit said rotational degrees of freedom (32, 34) of saiduniversal joint mechanism, and sensor means for detecting the rotationstresses in said universal joint mechanisms in correspondence of therotation axes of said rotational degrees of freedom (32, 34).